Two-way valves are often utilized in refrigeration systems wherein a plurality of conduits, usually three, connect to the valve, and operation of the valve selectively permits the interconnecting of two of the conduits while closing flow through the third conduit. Such valves are usually of a concise configuration, generally tubular or cylindrical in form, are formed of two or more parts brazed together, and the valve body usually includes at least one threaded adapter of standard configuration for accepting a connector fitting utilizing a compression nut or the like and other adapters or conduit fittings may be brazed to the body at spaced locations to accommodate the several conduits associated with the valve.
Refrigeration valve bodies normally consist of at least two parts to permit assembly of the valve, fabrication of the adapters, and the like. The normal process of fabricating refrigeration valve bodies is to braze the valve body components together at high temperatures, and it is also common to braze adapters or other conduit coupling connectors to the valve body. As brazing assembly techniques require high heat, heretofore, it has not been possible to utilize elastomeric seals with two-way refrigeration valves as the elastomer is damaged by the heat required during assembly, and in the past, only metal-to-metal sealing between the valve body and the valve head has been available.
It is an object of the invention to provide a refrigeration valve of the two-way type wherein an elastomeric seal may be used with the valve, and dependable sealing characteristics achieved.
Another object of the invention is to provide a two-way refrigeration valve employing an elastomeric seal wherein previously experienced leakage problems with valves using metal-to-metal sealing have been substantially eliminated.
Another object of the invention is to provide a two-way refrigeration valve employing an elastomer wherein the torque required to achieve acceptable sealing is substantially reduced with respect to prior valve constructions.
Yet another object of the invention is to provide a two-way refrigeration valve which employs both elastomeric and metal-to-metal sealing.
A further object of the invention is to provide a two-way refrigeration valve of such construction that the valve parts may be separately plated prior to assembly and the plating reduces the occurrence of rust within the valve and its chamber.
In the practice of the invention a valve body consists of at least two parts which are adapted to be brazed into permanent connection. The valve body includes an internal chamber having conical metal sealing surfaces defined therein in an opposed spaced relationship, and a valve member having a threaded stem cooperating with a threaded bore formed in the valve body mounts the head within the chamber and permits positioning of the head between the chamber sealing surfaces.
The valve head includes a central region and conical sealing surfaces converging in a direction away from the central region, and the valve head central region includes a peripheral or circumferential groove in which an elastomeric seal is located. The elastomer seal in the preferred construction is of a T-configuration having a column received within the valve head groove, and a cross bar constituting the periphery of the valve head has ends which extend in radial direction beyond the associated valve head conical surface.
The construction of the valve head elastomer permits the elastomeric material to engage the valve body chamber sealing surfaces prior to the engagement of the adjacent chamber and valve head metal sealing surfaces. Accordingly, it is possible to achieve an acceptable seal with only an elastomeric material engagement with the metal valve body sealing surface. However, if optimum sealing is required it is possible to compress the elastomer to the extent that the metal sealing surface of the valve head directly engages the metal valve body chamber sealing surface simultaneously producing metal-to-metal engagement as well as elastomeric to metal contact.
One of the valve body chamber sealing surfaces is defined upon an adapter part of the valve body which is brazed to the primary valve body. Accordingly, the valve body chamber is only completely defined once the adapter part is brazed to the primary part. The fact that the adapter valve body part is in directly opposed relationship to the chamber other sealing surface permits the enlarged head of the valve member to be readily installed within the valve body chamber, and upon brazing of the adapter part to the primary part the opposed chamber sealing surfaces may be selectively engaged by the valve head elastomer and the metal conical sealing surfaces defined thereon.
As the elastomer is located upon the periphery of the valve head the elastomer is not damaged during the brazing of the adapter part to the primary valve part, or during other brazing, if the valve head is centrally located within the chamber so that the elastomer will not be in engagement with any of the valve body sealing or metal surfaces, but rather, is spaced therefrom. Accordingly, that heat which is transferred to the valve head through the valve member stem, or by radiation or convection, is not of such extent as to deleteriously affect the valve head elastomer. Likewise, the centering of the valve head within the valve body chamber during subsequent brazing operations on the valve body so as to add conduits or conduit adapters to the valve head will not destroy the sealing characteristics of the elastomer.